Activation of hepatic acetyl-CoA carboxylase by glutamate and Mg2+ is mediated by protein phosphatase-2A.
(1996) The Biochemical journal — Vol. 316 ( Pt 1), p. 217-224 (1996)
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- The activation of hepatic acetyl-CoA carboxylase by Na(+)-cotransported amino acids such as glutamine has been attributed mainly to the stimulation of its dephosphorylation by accumulating dicarboxylic acids, e.g. glutamate. We report here on a hepatic species of protein phosphatase-2A that activates acetyl-CoA carboxylase in the presence of physiological concentrations of glutamate or Mg2+ and, under these conditions, accounts for virtually all the hepatic acetyl-CoA carboxylase phosphatase activity. Glutamate also stimulated the dephosphorylation of a synthetic pentadecapeptide encompassing the Ser-79 phosphorylation site of rat acetyl-CoA carboxylase, but did not affect the dephosphorylation of other substrates such as phosphorylase. Conversely, protamine, which stimulated the dephosphorylation of phosphorylase, inhibited the activation of acetyl-CoA carboxylase. A comparison with various species of muscle protein phosphatase-2A showed that the stimulatory effects of glutamate and Mg2+ on the acetyl-CoA carboxylase phosphatase activity are largely mediated by the regulatory A subunit. Glutamate and Mg2+ emerge from our study as novel regulators of protein phosphatase-2A when acting on acetyl-CoA carboxylase.
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Gaussin, V., Hue, L., Stalmans, W., & Bollen, M. (1996). Activation of hepatic acetyl-CoA carboxylase by glutamate and Mg2+ is mediated by protein phosphatase-2A. The Biochemical journal, 316 ( Pt 1), 217-224. https://hdl.handle.net/2078.5/136928 (Original work published 1996)